Dylank811 Posted October 12, 2011 Report Share Posted October 12, 2011 I may be interested in building a t-line box for 2 10" P3's. Anyone have any experience with these? They are in a ported box right now. It's either going to be the t-line box or some DC Level 2 15" subs. 2004 Ford Mustang GTPioneer DEH-P7200HD head unitMach 460 Factory System Cadence FXA1600.2 Cadence S2W10 Cadence 4 AWG wiring Ported box, 2 cubes, 32 hertz Link to comment Share on other sites More sharing options...
Firemanes Comin Posted October 14, 2011 Report Share Posted October 14, 2011 I'm trying to build a tapered variation T line since I dont have the truck space for a traditional T line. What I have designed is kind of like a reverse horn. If I were to build the traditional T-line as described in the first post in the thread, the line would be 106" long for my goals. Since I don't have the space for that, I went with a tapered design which I have calculated my design to be 66" long. Now, does the length of mine have to be the same (106") as the traditional to reach my goal of it being tuned to 32 hz? My enclosure is 12.75H x 31.5W x 17.5D and is for a IA Death Penalty 12" The mouth is 4 7/16" wide x 11.25" tall where the throat area is 9" wide x 11.25" tall. Link to comment Share on other sites More sharing options...
Firemanes Comin Posted October 14, 2011 Report Share Posted October 14, 2011 Also, I plan on putting 45's in the corners I just havent got to that point yet in my design. The 2 corners at the left of the enclosure will have 45's of equal length, while the corner in the upper right leading to the mouth of the enclosure should have a smaller 45. PWK sent me a design for 2 1508s, I used his design, scaled it to my available space,and I think I figured out his formula for designing these. Link to comment Share on other sites More sharing options...
STEvil Posted October 15, 2011 Report Share Posted October 15, 2011 Yes, the length needs to be the same. Your taper is in the wrong direction. MickyMcD - "Capable of making some serious trouser flapping volumes at where's-my-testicles frequencies, the Servo-Drives used to be fairly jaw dropping..." Any time you have have a power wire next to your frame put some rubber hosing (or cut up an innertube) around it. The wire is bound to wiggle (due to driving or flex) and the casing will eventually wear through. Hammerdown... 1% no links to outside websites, business related FB/YT pages allowed. Link to comment Share on other sites More sharing options...
Firemanes Comin Posted October 17, 2011 Report Share Posted October 17, 2011 Yes, the length needs to be the same. Your taper is in the wrong direction. After more research, I found out that the length does not need to be the same. Actually, the tapering of the walls lowers the enclosure's tuning. I will try to find the link so others can see the document. But I got the link off this site. Here's the info copied and pasted. It's long but a very good read. It has response graphs that didnt carry over from the copy/paste. There is more info on "traditional" t lines in the document. Line taper is somewhat different. But first, let’s discuss taper style, and their incidental benefits. Looking at the illustration linked to below you will see two types of taper. 1. is the traditional continuous taper, where CSA is constantly changing throughout the length of the line (in this case a common single-fold design). This design maximises the line-taper effect, with the incidental benefit that the line does not have parallel sides, and thus negates spurious inter-panel and inter-section resonances. 2. is what I refer to as a linear taper. The CSA of a section remains the same throughout it’s length, but the CSA of proceeding sections is reduced in comparison. This is far simpler to execute, but has reduced effect of the constant taper, especially in resonance control. As with line CSA, there are theoretically no limits to the ratio of line taper you can design – practicality again being the determining factor. 2:1 is popular, and feasible without obviating optimisation of the design. Bear in mind that this is a ratio, and so covers a variety of dimensional designs: i.e. 2 x Sd at the closed end, and Sd at the terminus. Or 3 x Sd at the closed end, and 1.5 x Sd at the terminus. Above 2:1, perhaps 3:1, really requires optimisation, perhaps modelling, and certainly a nod towards driver suitability. The effect of increasing taper ratio, primarily, is to lower the tuning of the line, by a marked degree, even for modest tapers. If the line is suitably damped, roll-off is shallower (at a theoretical minimum of 12dB/oct), allowing for extension into the sub bass. Frequency-wise, the harmonics do not change, so that the effective distance between the first one (actually the 3rd harmonic), and the fundamental (tuning frequency) increases – a potential benefit to bandwidth-limited designs. For those of a wider bandwidth of operation, the 3rd harmonic is reduced in level, as energy is spread into the low-bass by virtue of the lowering of resonant (tuning) frequency. Imagine an old-style tent: pegged out normally, it can sleep two, with enough room to manoeuvre. However, if you spread the base out, lowering the peak of the tent, you may be able to fit another person in, albeit with far less room for manoeuvre. The moral?. Everything’s a compromise. As energy is spread into the low bass, increasing bandwidth, there is a corresponding drop in efficiency at the (lowered) tuning frequency (the tent is not so peaked). This becomes more apparent as taper ratio increases. Fortunately, the lack of practicality of increasing taper ratios means that excessive effect is limited. However, even a modest taper may be sufficient, allied to a low Q (Qts) speaker/subwoofer to cause a drop in efficiency that relates sonically to a weak bass response. There is a flip side to this taper issue. If we know that tapering a line lowers the resonant frequency of the line, and that resonant frequency of the line is otherwise controlled by line length – why not reduce the length of the line?. Why not indeed. In doing so, retaining the desired tuning frequency, allied to the other benefits of tapering, with the additional benefit of reduced line length. Which, given the potential size of a low-tuned transmission line, is a considerable bonus. The problem is that this really is a function of line calculation and optimisation. That said, it shouldn’t deter the ardent experimenter – to whom I give, derived from experience, a ‘fudge factor’ of 0.8. For tapers of 2:1, perhaps even 3:1, reduce the ¼ wavelength-derived line length by a factor of 0.8 (this also takes care of boundary end-correction). So, our 40Hz example would become: Wavelength = 1120/(4f) =1120/(4*40) = 7ft (84”) 84*0.8 = 67” app. Link to comment Share on other sites More sharing options...
Firemanes Comin Posted October 17, 2011 Report Share Posted October 17, 2011 Here's the link for the document http://www.killahertz-acoustics.co.uk/TLdesign.doc Link to comment Share on other sites More sharing options...
blankskater08 Posted October 18, 2011 Report Share Posted October 18, 2011 Ive built one t-line and it hits pretty low. Im thinking about doing one for another 8" I have laying around but its f/s is 35hz. Thats like a 8 foot port. What difference would I hear if I shortend the port (raising the frequency)? Old Build Log -2001 Sc2 Build w/ Full Range 8" Rears Other Installs! -06' PT Cruiser w/ Four P2 8s! -Installs for Funsies Link to comment Share on other sites More sharing options...
STEvil Posted October 18, 2011 Report Share Posted October 18, 2011 Here's the link for the document http://www.killahertz-acoustics.co.uk/TLdesign.doc Not sure what I was thinking before.. but yes the change in orientation of the taper will add an increased "ported" style response to the enclosure vs a standard T-line.. I would say the correction factor will float depending on design. In a 1/4 wave box I would say it might be closer to .76.. maybe. MickyMcD - "Capable of making some serious trouser flapping volumes at where's-my-testicles frequencies, the Servo-Drives used to be fairly jaw dropping..." Any time you have have a power wire next to your frame put some rubber hosing (or cut up an innertube) around it. The wire is bound to wiggle (due to driving or flex) and the casing will eventually wear through. Hammerdown... 1% no links to outside websites, business related FB/YT pages allowed. Link to comment Share on other sites More sharing options...
AmericanLegend Posted October 19, 2011 Report Share Posted October 19, 2011 Here's the link for the document http://www.killahertz-acoustics.co.uk/TLdesign.doc That was a good read; thanks! Link to comment Share on other sites More sharing options...
SteveBrondstetter Posted October 23, 2011 Report Share Posted October 23, 2011 Just thought i would toss up my T-line build for the Atomic AP8 Also tested with a DC8" the little thing rocks! I have been building T-lines for a couple years now. Oh and hi everyone since this is my first post My link My link My link My link http://www.facebook.com/pages/Altimate-Automotive/121314931239071 www.altimateautomotive.com The Zombie's are coming Steve Link to comment Share on other sites More sharing options...
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